Attempts to measure adequacy of EMS systems must insure that comparable groups of patients are being studied. Accurate methods are needed to describe and classify patients with regard to degree of severity. This research will: Develop and test two severity index development strategies in terms of their ability to create reliable, sensitive and acceptable severity indices. Develop severity indices for four EMS conditions and evaluate their reliability, sensitivity and acceptability. Evaluate the impact of expert's specialty, institutional setting and conflict resolution style on the index reliability, sensitivity and acceptability. Demonstrate the utility of the index in classifying patients for evaluating EMS systems. The indexing methodologies (both decision theoretic) have been used by the investigators to index medical underservice for HEW and to measure the severity of burns.